From Nitrobenzenes to Substituted Tetrahydroquinolines in a Single Step by a Domino Reduction/Imine Formation/Aza-Diels-Alder Reaction

The three-component reaction between a nitrobenzene, an aldehyde, and a dienophile in the presence of iron powder as a reductant and montmorillonite K10 as a catalyst in aqueous citric acid delivers the products of an aza-DielsAlder (Povarov) reaction with high endo-selectivity and yields up to 99%.